Sound reproducing device



Sept. 8, 1931. I M. NYSTROMV 1,822,450

SOUND REPRODUCING DEVI CE Filed April 10, 1926 ceeds.

Patented Sept. 8, 1931 UNITED STATES.

PATENT OFFICE MARTIN NYSTROM, .OF CHICAGO, ILLINOIS,- ASSIGNOB, BY MESNE ASSIGNMENTS, TO

TION on DELAWARE ,Appli'cation filed April 10,

like action whereby especial sensitiveness will 7 be assured and the reproduction will be rendered faithful over a wide range of frequencies.

Another object of the invention is to provide an extremely thin and therefore sensitive diaphragm with central reinforcing piecesengaging the sameat the center for preventing central flexure and undesirable Vibrations which accompany such flexure.

A further object of the invention is to provide a thin diaphragm having light reinforcing pieces on opposite sides of its central portion with deformations for preventing flex-' me of the central portion.

A still further object of theinvention is to provide light and durable means for clamping reinforcing pieces to the center of a diaphragm and securing the diaphragm to a vibratory member for actuating the diaphragm.

Other objects and advantages of the in vent-ion will appear as In the accompanying drawings Fig. 1 is acentral sectional view on a large scale of a sound box, illustrating the invention.

Fig. 2 is a side elevational view of the .sound box shown in Fig. 1, aportion of a guard being broken away to disclose parts enclosedthereby, and Fig. 3 is a detail side elevational view of the diaphragm, parts thereof being broken away.

In order that the diaphragm 1 maybe very sensitive it is' made of minimum mass and is extremely thin. 'It may be approximately' .002 in thickness, and composed of a light metal such as aluminum or an aluminum alloy. The outerportion of the dia= phragm is flexible and to facilitate flexure, maybe provided with annular corrugations 2 of suitable number.

the description pro i the spre UNITED RESEARCH CORPORATION, OF LONG ISLAND CITY, NEW YORK, A CORPORA- sounn REPRODUCING DEVICE 1926. Serial No. 101,185.

An annular deformation 3 may be provided for making the center of the diaphragm rigid and it may be so formed that its sides and substantially trunco conical in shape. Interiorly of the deformation 3 the diaphragm may be formed. into a cone4' and is therefore rendered inflexible throughout this area.

The center of the diaphragm may be further strengthened by a pair of reinforcing pieces 5 and 6 which may fit snugly against its opposite faces, and which may conform' closely to the shape of the cone 4 and the deformation 3. The reinforcing pieces may be provided with deformations 7 and 8, similar to the deformation 3, and are of very low mass. They may be composed of alight metal such as aluminum or an aluminum alloy and I may be approximately .002" in thickness.

Radial indentations may also be provided for further stiffening the reinforcing pieces and the diaphragm. Indentations 9 in the reinforcing piece 6 may be superimposed on and nest in similar indentations 9 in the cone 1 and those in the cone may be superimposed on and nest in similar indentations 9 in the reinforcing piece 5. The rigidity of the center is such that in its vibratory movement it acts as apiston the tendency to flex and set up undesirable vibrations being eliminated.

'For securing the stylus bar 10 to the diaphragm 1, the apex of the cone 4 and the ad'- jacent portions of the reinforcing pieces 5 and 6 may be provided with registering apertures to receive the shank 11 of a rivet which may be provided with a head 12 for engaging the reinforcing piece 5. The rivet may be composed of a light metal such as aluminum or an aluminum alloy and may clamp a ring 13 of suitable metal such as brass against the reinforcing piece 6. The portions betweenthe rivet head 12 and the ring 13 may be slightly flattened so as to be securely gripped. The ring 13 may be countersunk at 14 to permit the rivet to be spread therein.

The stylus bar 10 may be made of suitable material such as steel and may be rigidly secured to the ring 13 by solder 15. The stylus bar may 1 dished at 16 to provide room for end of the rivet, and may have greatly enhanced yet at the same time the stylus bar is secured rigidly to tlie diaphragm i flattened terminals 17 seating snugly against the ring 13.

Such a diaphragm embodying the inven undesirable vibrations. V Yet, notwithstanding its extreme sensitiveness, it is very durable and shows no tendency to deteriorate even after long usage. The central portion of thediaphragmdoes not tend to collapse, but retains its shape per manently, andits rigidity enables it to vibrate in operation with a piston like action.

It will be apparent that the described means for securing the stylus bar to the-diaphragm will have a minimumweight as the parts are small and of minimum mass. The sensitiveness of the diaphragm and its-readiness to respond to the impulses of the stylus bar are in such a-manner that there is no possibility of the stylus bar tearing loose.

" this movement and preventing accidental The stylus bar 10 may be mounted for pivotal movement in any desired manner and stops 18 and 19 may be provided for limiting deformation of the diaphragm. V

The outer portion of the diaphragm 1 is 'flatand may be held between a pair of washers 20, which maywbepressedbetween a cap 21 and a plate 22. A clamping ring 23 in threaded engagement with thecap 21 may be. for holding the latter securely in position. Theface of the plate 22 is spaced provided.

slightly from the diaphragm to provide a .002" in thickness, composedof an extremely light metal and having a conical center surrounded b an annular deformation, the walls of which are oppositely inclined and a relatively narrow outer portion deformed to facilitate flexure and permit piston-like movement of the center.

3. The combination of a thin diaphragm having a flexible outer portion and a pair of reinforcing members lying along opposite faces ofthe center of reinforcing members and sai havin dial eformations for preventing flexure of the center of said diaphragm.

4.' The combination with an extremely thin diaphragm-having a flexible outer portion and a rigid center of the shape of a cone, of a pair of reinforcing members secured to said diaphragm and lying along opposite faces of said cone, said diaphragm and said members havin similar superimposed, space radial deformations flexure of the center of said diaphragm.

' 5. The combination of a diaphragm having a flexible outer portion and a. rigid substantially cone shaped center, and a pair of diaphragm said diaphragm, said superimposed, annularly spaced, ra-- annularly for preventing q reinforcmg members secured to said diaphragm and l in along opposite faces of said center, sald iaphragm and said membershaving similar superimposed, annularly spaced, radial deformations for pr'eventing' flexure ofthe center of said diaphragm, said membersand said dia' hragm beln'g composed of an extremely lig t metal and being extremel thin. L

Signed at Chicago, State of 111., United States of America, this 9day of April A.-D., 1926. MARTIN NYSTROM.

shallow air chamber and may be provided with an annular recess 24 adjacent the edge of the reinforcing piece 5 to permit the diaphragm 1 to move toward the plate 22. The plate 22 may also have an annular rib 25 ad- 1 jacent the deformation 7 which will permit imovement of the diaphragm but reducethe volumne of the air chamber so that it may be made quite small. The inner face of the rib 25 may converge into a throat 26. v ".The invention is not limitedto the embodiment'illu'strated and described, which may be modified extensively within the spirit of the invention and a substantial rangeof equivalents is'contemplated-within the scope of the appended claims.

Iclaimf A 1. A thin diaphragm having a conical cen-v ter surrounded by an annular deformation the walls of which are oppositely inclined anda relatively, narrow out-er portion deformed to facilitate flexure thereof and permit the center to move as a piston.

12. An acoustic diaphragm approximately 

